AbstractAlfvén waves play critical roles in the electrodynamic coupling of plasmas at magnetically conjugate regions in near‐Earth space. Associated electric (E*) and magnetic (δB*) field perturbations sampled by sensors on satellites in low‐Earth orbits are generally superpositions of incident and reflected waves. However, lack of knowledge about ionospheric reflection coefficients (α) hinders understanding of generator outputs and load absorption of Alfvén wave energies. Here we demonstrate a new method for estimating α using satellite measurements of ambient E* and δB* then apply it to a case in which the Communication/Navigation Outage Forecasting System (C/NOFS) satellite flew conjugate to the field of view of a 630.0 nm all‐sky imager at El Leoncito, Argentina, while medium‐scale traveling ionosphere disturbances were detected in its field of view. In regions of relatively large amplitudes of E* and δB*, calculated α values ranged between 0.67 and 0.88. This implies that due to impedance mismatches, the generator ionosphere puts out significantly more electromagnetic energy than the load can absorb. Our analysis also uncovered caveats concerning the method's range of applicability in regions of low E* and δB*. The method can be validated in future satellite‐based auroral studies where energetic particle precipitation fluxes can be used to make independent estimates of α.